Synthesis and in vitro study of nitro- and methoxy-2-phenylbenzofurans as human monoamine oxidase inhibitors

Potent, selective and reversible hMAO-B inhibition by benzalphthalides: Synthesis, enzymatic and cellular evaluations and virtual docking and predictive studies

Monoaminooxidases (MAOs) are important targets for drugs used in the treatment of neurological and psychiatric disorders and particularly on Parkinson's Disease (PD). Compounds containing a trans-stilbenoid skeleton have demonstrated good selective and reversible MAO-B inhibition. Here, twenty-two (Z)-3-benzylidenephthalides (benzalphthalides, BPHs) displaying a trans-stilbenoid skeleton have been synthesised and evaluated as inhibitors of the MAO-A and MAO-B isoforms. Some BPHs have selectively inhibited MAO-B, with IC50 values ranging from sub-nM to μM. The most potent compound with IC50 = 0.6 nM was the 3',4'-dichloro-BPH 16, which showed highly selective and reversible MAO-B inhibitory activity. Furthermore, the most selective BPHs displayed a significant protection against the apoptosis, and mitochondrial toxic effects induced by 6-hydroxydopamine (6OHDA) on SH-SY5Y cells, used as a cellular model of PD. The results of virtual binding studies on the most potent compounds docked in MAO-B and MAO-A were in agreement with the potencies and selectivity indexes found experimentally. Additionally, related to toxicity risks, drug-likeness and ADME properties, the predictions found for the most relevant BPHs in this research were within those ranges established for drug candidates.

Probing the inhibition of MAO-B by chalcones: an integrated approach combining molecular docking, ADME analysis, MD simulation, and MM-PBSA calculations

CONTEXT

Monoamine oxidase B (MAO-B), an enzyme of significant relevance in the realm of neurodegenerative disorders, has garnered considerable attention as a potential target for therapeutic intervention. Natural compounds known as chalcones have shown potential as MAO-B inhibitors. In this particular study, we employed a multimodal computational method to evaluate the inhibitory effects of chalcones on MAO-B.

METHODS

Molecular docking methods were used to study and assess the complicated binding interactions that occur between chalcones and MAO-B. This extensive analysis provided a valuable and deep understanding of possible binding methods as well as the key residues implicated in the inhibition process. Furthermore, the ADME investigation gave valuable insights into the pharmacokinetic properties of chalcones. This allowed them to be assessed in terms of drug-like attributes. The use of MD simulations has benefited in the research of ligand-protein interactions' dynamic behaviour and temporal stability. MM-PBSA calculations were also done to estimate the binding free energies and acquire a better knowledge and understanding of the binding affinity between chalcones and MAO-B. Our thorough method gives a thorough knowledge of chalcones' potential as MAO-B inhibitors, which will be useful for future experimental validation and drug development efforts in the context of neurodegenerative illnesses.

Design, synthesis, and biological activity of dual monoamine oxidase A and heat shock protein 90 inhibitors, N-Methylpropargylamine-conjugated 4-isopropylresorcinol for glioblastoma

Monoamine oxidase A (MAO A) and heat shock protein 90 (HSP90) inhibitors have been shown to decrease the progression of glioblastoma (GBM) and other cancers. In this study, a series of MAO A/HSP90 dual inhibitors were designed and synthesized in the hope to develop more effective treatment of GBM. Compounds 4-b and 4-c are conjugates of isopropylresorcinol (pharmacophore of HSP90 inhibitor) with the phenyl group of clorgyline (MAO A inhibitor) by a tertiary amide bond substituted with methyl (4-b) or ethyl (4-c) group, respectively. They inhibited MAO A activity, HSP90 binding, and the growth of both TMZ-sensitive and -resistant GBM cells. Western blots showed that they increased HSP70 expression indicating reduced function of HSP90, reduced HER2 and phospho-Akt expression similar to MAO A or HSP90 inhibitor itself. Both compounds decreased IFN-γ induced PD-L1 expression in GL26 cells, suggesting they can act as immune checkpoint inhibitor. Further, they reduced tumor growth in GL26 mouse model. NCI-60 analysis showed they also inhibited the growth of colon cancer, leukemia, non-small cell lung and other cancers. Taken together, this study demonstrates MAO A/HSP90 dual inhibitors 4-b and 4-c reduced the growth of GBM and other cancers, and they have potential to inhibit tumor immune escape.

Design and synthesis of functionalized 4-aryl-Catechol derivatives as new antiinflammtory agents with in vivo efficacy

Oxidative stress and inflammation are two conditions that coexist in many multifactorial diseases and the discovery of antioxidants is an attractive approach that can simultaneously tackle two or more therapeutic targets of the arachidonic acid cascade. We report that the simple structural variations on the 4-aryl-benzene-1,2-diol side-arm of the scaffold significantly influence the selectivity against 5-LOX vs 12- and 15-LOX. Derivatives 4 a-l were evaluated for their antioxidant activity, using the DPPH, and ferric ion reducing antioxidant power (FRAP) methods. Docking simulations proposed concrete binding of the catechol series to 5-LO. Selected active compound 4-(3,4-dihydroxyphenyl)dibenzofuran (4l) was also tested in different in vivo mouse models of inflammation. 4l (0.1 mg/kg; i.p.) impaired (I) bronchoconstriction in ovalbumin-sensitized mice challenged with acetylcholine, (II) exudate formation in carrageenan-induced paw edema, and (III) zymosan-induced leukocyte infiltration in air pouches. These results pave the way for investigating the therapeutic potential of 4-aryl-benzene-1,2-diol, as novel multitarget therapeutic drugs, able to regulate the complex inflammatory cascade mechanisms.

Design, Synthesis, and Monoamine Oxidase B Selective Inhibitory Activity of N-Arylated Heliamine Analogues

Monoamine oxidase B (MAO-B) metabolizes monoamines such as dopamine regarding neural transmission and controls its level in the mammalian's brain. When MAO-B metabolizes dopamine abnormally, normal neurotransmission does not occur, and central nervous system disorders such as Parkinson's disease may develop. Although several MAO inhibitors have been developed, most of them have no selectivity between monoamine oxidase A (MAO-A) and MAO-B, or they work irreversibly against the enzyme. This report describes the first case of screening of N-arylated heliamine derivatives to develop novel MAO-B selective inhibitors that can be synthesized concisely by microwave-assisted Pd nanoparticle-catalyzed Buchwald-Hartwig amination. We discovered that the derivatives 4h, 4i, and 4j display inhibitory activity against MAO-B with IC50 values of 1.55, 13.5, and 5.08 μM, respectively.

Monoamine oxidase inhibitors: A concise review with special emphasis on structure activity relationship studies

Monoamine oxidase enzyme is necessary for the management of brain functions. It oxidatively metabolizes monoamines and produces ammonia, aldehyde and hydrogen peroxide as by-products. Excessive production of by-products of monoamine metabolism generates free radicals which cause cellular apoptosis and several neurodegenerative disorders for example Alzheimer's disease, Parkinson's disease, depression and autism. The inhibition of MAOs is an attractive target for the treatment of neurological disorders. Clinically approved MAO inhibitors for example selegiline, rasagiline, clorgyline, pargyline etc. are irreversible in nature and cause some adverse effects while recently studied reversible MAO inhibitors are devoid of harmful effects of old monoamine oxidase inhibitors. In this review article we have listed various synthesized molecules containing different moieties like coumarin, chalcone, thiazole, thiourea, caffeine, pyrazole, chromone etc. along with their activity, mode of action, structure activity relationship and molecular docking studies.

Resveratrol-Based MTDLs to Stimulate Defensive and Regenerative Pathways and Block Early Events in Neurodegenerative Cascades

By replacing a phenolic ring of (E)-resveratrol with an 1,3,4-oxadiazol-2(3H)-one heterocycle, new resveratrol-based multitarget-directed ligands (MTDLs) were obtained. They were evaluated in several assays related to oxidative stress and inflammation (monoamine oxidases, nuclear erythroid 2-related factor, quinone reductase-2, and oxygen radical trapping) and then in experiments of increasing complexity (neurogenic properties and neuroprotection vs okadaic acid). 5-[(E)-2-(4-Methoxyphenyl)ethenyl]-3-(prop-2-yn-1-yl)-1,3,4-oxadiazol-2(3H)-one (4e) showed a well-balanced MTDL profile: cellular activation of the NRF2-ARE pathway (CD = 9.83 μM), selective inhibition of both hMAO-B and QR2 (IC₅₀s = 8.05 and 0.57 μM), and the best ability to promote hippocampal neurogenesis. It showed a good drug-like profile (positive in vitro central nervous system permeability, good physiological solubility, no glutathione conjugation, and lack of PAINS or Lipinski alerts) and exerted neuroprotective and antioxidant actions in both acute and chronic Alzheimer models using hippocampal tissues. Thus, 4e is an interesting MTDL that could stimulate defensive and regenerative pathways and block early events in neurodegenerative cascades.

Structural Insight of New Butyrylcholinesterase Inhibitors Based on Benzylbenzofuran Scaffold

In the present work, we use a merger of computational and biochemical techniques as a rational guideline for structural modification of benzofuran derivatives to find pertinent structural features for the butyrylcholinesterase inhibitory activity and selectivity. Previously, we revealed a series of 2-phenylbenzofuran compounds that displayed a selective inhibitory activity for BChE. Here, in an effort to discover novel selective BChE inhibitors with favorable physicochemical and pharmacokinetic profiles, 2-benzylbenzofurans were designed, synthesized, and evaluated as BChE inhibitors. The 2-phenylbenzofuran scaffold structure is modified by introducing one methylene spacer between the benzofuran core and the 2-phenyl ring with a hydroxyl substituent in the para or meta position. Either position 5 or 7 of the benzofuran scaffold was substituted with a bromine or chlorine atom. Further assessment of the selected list of compounds indicated that the substituent’s nature and position determined their activity and selectivity. 5-bromo-2-(4-hydroxybenzyl)benzofuran 9B proved to be the most potent butyrylcholinesterase inhibitor (IC₅₀ = 2.93 µM) of the studied series. Computational studies were carried out to correlate the theoretical and experimental binding affinity of the compounds to the BChE protein.

Gamma-decanolactone: Preliminary evaluation as potential antiparkinsonian drug

Treatment of Parkinson's disease (PD) includes the use of monoamine oxidase-B (MAO-B) inhibitor drugs. In this work we have evaluated the possible gamma-decanolactone (GD) effect in vitro to inhibit the A and B isoforms of human monoamine oxidase (hMAO) enzyme and their citotoxicity in human hepatoma cell line (HepG2). Also, binding studies to A₁, A_2A A_2B and A₃ adenosine receptors were performed. A docking study of gamma-decanolactone has been carried out with the molecular targets of MAO-A and MAO-B isoforms. The physicochemical properties and ability to cross physiological barriers, as the blood brain barrier (BBB), was elucidated by computational studies. The in vivo assays, the rota-rod test, body temperature assessment and open field test were performed in reserpinized mice (1.5 mg/kg, i.p.; 18:00 before) to evaluate the effect of gamma-decanolactone (300 mg/kg), alone or associated with Levodopa plus Benserazide (LD + BZ, 100:25 mg/kg, i.p.). Gamma-decanolactone inhibited preferentially the MAO-B in a reversible manner, with an inhibitory concentration of 50% (IC₅₀) 55.95 ± 9.06 μM. It was shown to be a safe drug since only at the highest concentration decreased the viability of HepG2 cells. It also does not bind to adenosine receptors investigated in this study. The molecular docking study show that the gamma-decanolactone ligand adopts a relatively compact conformation in the active site of hMAO-B, while we note an extended conformation of gamma-decanolactone ligand in the hMAO-A isoform. The physicochemical properties obtained, and the theoretical models utilized for the evaluation of ability to cross the BBB, predict a good gamma-decanolactone bioavailability and access to the central nervous system (CNS). In the in vivo studies, gamma-decanolactone partially reversed the ataxia of the reserpinized mice at 01:00 h and 01:30 h post-administration. Concomitant treatment of gamma-decanolactone with LD + BZ, at 01:30 h showed a potentiation of the reversibility of ataxia and facilitated the reversal of hypothermia caused by reserpine for all measured times (P <0.01 vs vehicle), except at 24:00 h, but not reversed the hypokinesia in the open field test. In summary, the results herein obtained and in conjunction with previous studies, suggest that gamma-decanolactone could be a drug with potential utility as antiparkinsonian drug.

Novel 2,5-disubstituted-1,3,4-oxadiazole derivatives as MAO-B inhibitors: Synthesis, biological evaluation and molecular modeling studies

Thirty novel 2,5-disubstituted-1,3,4-oxadiazole derivatives bearing urea moiety were designed and synthesized. IR, ¹H-NMR, ¹³C-NMR and mass spectroscopic methods and elemental analysis were used to confirm the structures of the compounds. Their monoamine oxidase inhibitory activity was determined against the MAO-A and MAO-B isoforms. None of the compounds showed the potent MAO-A inhibitory activity, while the MAO-B inhibition was significantly found in the range of 62 to 98%. Among them, the compounds H8, H9 and H12 bearing chloro substituent at the fourth position of phenylurea were found to show potent monoamine oxidase B inhibitory activity with IC₅₀ values 0.039-0.066 µM. To define and evaluate the interaction mechanism between compound H8 and monoamine oxidase B, molecular docking studies have been made.